Audio tracking collars have been used by hunters for many years to locate hunting dogs in situations in which visual identification of dogs is impaired by foliage, physical distance, inclement weather, etc. Audio tracking collars generally emit a high amplitude audio signal which provides directional information associated with an animal's location. Typical audio tracking collars produce an audio signal in the range of 2000 Hertz and above with approximately a 100 decibel minimum sound pressure level at 30 centimeters from the annunciator. The audio signal may be modulated or swept in frequency in order to provide a unique signal that can be used to discern one dog from another in situations herein multiple dogs are ranging, or to provide information about the behavior of a dog in such instances wherein the dog has treed a prey or has stopped moving or assumed a pointing stance.
Typical audio tracking collars use annunciating devices which comprise low cost piezoelectric elements that transduce an applied electric signal into an acoustically emitted signal. Such piezoelectric transducer systems offer limited functioning capability due to inherent design limitations. For example, such piezoelectric transducer systems tend to be resonate over a very narrow frequency range. Although such systems provide acceptable acoustic signal amplitude over their limited frequency ranges, these frequency range limitations restrict the complexity of signal modulation that the annunciators are capable of producing. Thus, these systems are limited in their ability to produce different discernable audio signals.
A number of prior art audio tracking collars have their annunciating elements mounted in such a manner that, when worn by an animal, the opening through which the audio signal emanates is pointed upwards. In such a configuration, rain and/or snow tends to fill the annunciator through the opening, resulting in a reduction in the amplitude of the audio signal. Debris such as brush and plant materials present in many outdoor sites can also obscure the opening and, if carried by water flow into the interior recesses of the annunciator, is virtually impossible to remove. Dogs that swim while wearing audio tracking collars cause the annunciators to fill with water and dissolved sediments.
The present invention provides acoustic annunciators for collar mounted audio signal devices which have frequency ranges that can be modulated and which are designed for rough field service.